Fermenting Fungi Faster to Quell Whiteflies

A fungus with a penchant for attacking and killing silverleaf
whiteflies and other crop pests could be the bioinsecticide to watch as
scientists on both sides of the U.S.-Mexico border work to make it commercially
viable.

Scientists with USDAs Agricultural Research Service collaborated
with Mycotech Corp. of Butte, Mont., to improve methods for economically
producing large numbers of spores of the fungus Paecilomycesfumosoroseus (pay-SILL-o-my-sees fume-o-so-ROSE-ee-us). These spores can
be spread in fields as a non-chemical, environmentally friendly weapon against
the crop pests.

The ARS scientists modified earlier deep-tank fermentation
technology that launched an arsenal of antibiotics against human disease. Since
applying for a patent less than two years ago, the researchers have doubled the
number of spores produced per tank and cut fermentation time from three days to
less than two.

To be commercially viable, large and predictable numbers of spores
produced months in advance of use may have to survive freeze-drying and
long-term storage. Then they must spring vigorously from this Rip Van Winkle
state when mixed with water and sprayed on insect pests.

In the latest benchmark achievement, 80 percent of spores that
survived freeze-drying were still viable after 5 months of storage. One crucial
difference: The scientists mixed the microbes with sustaining cornstarch, flour
and sucrose before drying them.

Scientists at the Universidad Autonoma de Nuevo Leon, Monterrey,
Mexico, have begun working with the ARS researchers to develop fermentation
media that are more economical than the precisely defined recipes used earlier.

The scientists in Mexico are also working with ARS scientists in
Weslaco, Texas, to make sure the spores do their job well in the greenhouse and
in the field.

To further improve the spore survival rate, the international
scientific team is conducting research to precisely define requirements for
storage environments. Such requirements may involve packaging and temperature
and humidity controls.